Clearing-out signaling apparatus.



No. 697,990. Patented Apr. 22, |902.

, W. M. DAVIS.

CLEARING-OUT SIGNALING APPARATUS.

(Appuminil med Jan. 11, 1901.)

(No Model.)

artnr FFICE.

IVILLIAM M. DAVIS, OF' CHICAGO, ILLINOIS, ASSIGNOR TO THE STROMBERG- CARLSON TELEPHONE MANUFACTURING COMPANY, OF CHICAGO, ILLI- NOIS, A CORPORATION OF ILLINOIS.

CLEARING-OUT SIGNALING APPARATUS.

SPECIFICATION forming part f Letters Patent No. 697,990, dated April 22, 1902.

Application lcd January 11, 1901. Serial No. ll2,9l4. (No model.)

To @ZZ wwm, it may concern:

Be it known that I, WILLIAM M. DAVIS, a citizen of the United States, residing at Chicago, in the county of Cook and State ot Illinois, have invented a certain new and useful Improvement in Clearing-Out Signaling Apparatus, (Case No. 10,) of which the following is a full, clear, concise, and exact description, reference being had to the accompany- 1o ing drawing, forming a part of this specification.

My invention relates to telephone-exchange systems, and has for its object the provision of improved clearing-out signaling means.

The invention in its preferred embodiment contemplates the provision of a telephoneexchange system wherein there are clearingout signaling devices, two for each cord-circuit, which jointly serve to convey a clearzo ing-out signal, while they act, respectively, to

indicate certain conditions of use of the calling and called subscribers telephone-lines. The signals that I prefer to employ are small electric lamps controlled by suitable relays.

By means of the invention the relay that controls the calling subscribers indicator is operated immediately upon the insertion ot' the answering-plug to prevent the signal-lamp controlled thereby from glowing. The called 3o subscriber, however, not having answered,

his telephone switch-hook is in its normal position, in which condition of use the relay controlling his supervisory signal is not operated, so that the lamp controllable thereby is caused to glow immediately upon the insertion of the connecting -plug within the called subscribers jack. lVhen the called subscriber removes his telephone from its switch-hook, the relay controlling his supervisory signalis actuated and the lamp ceases to glow. The receivers at the subscribers stations now both being removed from their switch-hooks, both relays are simultaneously in an operated position, so that during the conversation neither supervisory signal glows.

In accordance with my invention I provide a supplementary switching appliance controlled by the called subscribers supervisory relay that serves to place the relays simulta- 5o neously in circuit with a source of current,

the relays being preferably included in parallel relation, so that both relays will be restored to their normal condition simultaneously. To this end the relays in addition to being included in parallel circuit with each other are also preferably included by means of the said auxiliary switching appliance in bridge of the telephone-circuit, so that the relays cannot be restored to their normal idle condition until both receivers at the connect- 6o ed subscribers stations have been restored to their switch-hooks, whereupon both supervisory signals will simultaneously glow to convey a positive clearing-out signal. Prior to the actuation of the switch controlled by the called subscribers supervisory relay each relay is included in series with its associated telephone-circuit, while the battery for controlling the operation ofthe relays is included in bridge between the telephonelines, by 7o which arrangement each relayis adapted for immediate operation upon the elevation ofthe corresponding subscribers-telephone switchhook. The said auxiliary switch controlled by the called subscribers relay forms a short path for the' telephonic circuit4 between the connected stations, the relays then being included in bridge, as before stated, of the telephonic circuit.

I will explain my invention more fully by 8o reference to the accompanying drawing,which illustrates the preferred embodiment thereof as applied to a telephone-exchange.

In the drawing I have illustrated two telephone-stations A and B, each provided with a telephone switch-hook a, a telephone-receiver l), a transmitter c, and a signal-receiver d. The system illustrated herein is a common battery system, and therefore the substations are in this instance not provided v 9o with magneto-generators; but I do not wish to be limited to such a system. Each telephone-line extends by its limbs to the eX- change and is there connected with the tipline springs e and the sleeve-line springs f, three jacks of a multiple switchboard being here illustrated. Two plugs are preferably employed, having tips and sleeves connected by a tip-strand g and a sleeve-strand h. Relays or electromagncts it', that control the roo supervisory signals 7c aare normally included in the sleeve-strand, while a common battery l is included in bridge between one side of a telephone-line and the correspondingly opposite side of the cord-circuit, the latter connection being located between the relays.

Many forms of line-signals may be employed in the system of my present invention. The form illustrated comprises a relay having oppositely or differentially wound coils m n, which create equal opposing eiects. The armature 0 of the relay normally includes the coils of the relay in series with the common battery Z, that may be of forty Volts, and a line-indicator or the electromagnet of a lineindicator q. When a subscriber removes his telephone from its switch-hook, a circuit is completed through the coils ofthe relay and the magnet of the line-indicator, whereby a calling-signal is manifested, which callingsignal is maintained as long as the coils m and n exert their opposing effects, the armature o then remaining in its normal position. When the operator inserts a plug in response to a signal or in connecting a called subscriber, current from the battery l is principally confined to a path that includes the helix m, the tip line-spring of the engaged jack, the tip of the plug inserted within said jack, and thence through the cord-circuit instrumentalities to the battery. The current by being confined principally to this path of comparatively low resistance, the magnet of the line-indicator being preferably of iive hundred ohms produces a greater magnetizing effect in the coil m than in the coil n, whereby the armature o is attracted and circuit to the magnet of the line-indicator is broken. When a subscriber initiates a call, the operator inserts her answering-plug and actuates her listening-key to include her telephone in the circuit and ascertain the connection desired. When the answering-plug is thus inserted, the magnet 7l is included in the closed circuit that also includes the battery Z, the calling subscribers telephone-line and his telephone switch-hook with its engaging Contact, thereby immediately cutting the lamp /c out of circuit. The connecting-plug controls a similar circuit for the companion electromagnet t' corresponding to the called? subscribers line; but this electromagnet is not operated until the called subscriber removes his telephone from its switch-hook, so that until the called subscriber responds the signal k is included in a closed circuit to indicate to the operator that the called subscriber has not responded, which closed circuit is opened by the called subscribers supervisory relay when the said subscriber removes his telephone. His supervisory relay is provided with a supplemental switching appliance r, that serves to shunt the magnets 7l 't' from the sleeve-strand of the cordcircuit, so that the cord-circuit will contain no impedance. This switch r serves to complete a bridge connection that terminates at one end by electrical connection with the sleeve-strand and at the other end with the tip side ot' the telephone-line, this bridge connection including the magnets in parallel and.v

the common battery in series with the magnets.

The advantages ot the system herein disclosed are apparent to those skilled in the art.

While I preferably shunt the coils of the magnets of the indicators from the cord-circuit, Ido not wish to be limited to this particular way of removing the said coils.

While I have herein shown and particularly described the preferred embodiment of my invention, I do not wish to be limited to the precise disclosure herein set forth; but,

Having described my invention, I claim as new, and desire to secure by Letters Patent, the following:

l. Inatelephone-exchangesystem,thecoinbination with a telephone-line extending from a subscribers telephone-station to an exchange, of cord-connecting apparatus at the exchange for uniting subscribers for conversation, an indicator having its operating electromagnet included in circuit with the said telephone-line and serially in a cord-strand, a source of current, a telephone switch-hook at the subscribers station adapted when relieved of the innence of the telephone-receiver to close circuit through said battery and magnet of the indicator to correspondingly operate the indicator, and a switch with suitable connections, operated by the electromagnet when thus included in circuit, serving to shunt the electromagnet from its series connection with the cord-circuit and maintain said magnet in circuit with the said source ot current, whereby the signal may be maintained in the condition to which it has been brought while the electromagnet controlling the same is removed from the path of voicecurrents, the telephone switch-hook at the subscribers station, when actuated through the inliuence of the restored receiver, serving to open the circuit through the electromagnet of the indicator to restore the indicator, substantially as described.

2. In a telephone-exchange system,the combination with a telephone-line extending from a subscribers telephone-station to an exchange, of cord-connecting apparatus at the exchange, an indicator havingits operatingelectromagnet included in circuit with the said telephone-line and serially in a conductor forming a part of the telephonie circuit, a source of current, a telephone switch-hook at the subscribers station adapted when relieved from the influence of the telephone-receiver to close circuit through said battery and magnet of the indicator to correspondingly operate the indicator, and a switch with suitable connections, operated by the electromagnet when thus included in circuit, serving to shunt the electromagnet from the telephonie circuit and maintain the said magnet IIO in circuit with said source of current, whereby the signal may be maintained in the condition to which it has been brought, while the electrolnagnet controlling the same is removed from the path of voice-currents, the telephone switch -hook at the subscribers station, when actuated through the influence of the restored receiver, serving to open the circuit through the electromagnet of the indicator to restore the indicator, substantially as described.

3. Inate'lephone-exchange systeni,tl1e combination with telephone-lines extending from subscribers stations to an exchange, of cordconnecting apparatus at the exchange, indicators at the exchange having their electromagnets normally included serially in the cord-circuit, one of the said indicators being'. connected with the calling' subscriber and the other with the called subscriber, a telephone switch hook at each subscribers station adapted to close circuit through the magnet of the indicator connected therewith, and a switch with its connections operated by the called subscribers indicator magnet for shunting the said magnets from the cord-circuit and maintaining them in closed circuit, whereby the signals may be maintained in the condition in which they have been placed, substantially as described.

4. Inatelephone-exchangesystem,thecombination with telephone-lines extending from subscribers stations to an exchange, of cordconnecting'apparat-us at the exchange, indicators at the exchange having their electromagnets normally included serially in the cord-circuit, one of the said indicators being connected with the calling subscriber and the other with the called subscriber, a bridge con nection between the sides of united telephonelines including a source of current, a telephone switch-hook at each subscribers station adapted to close circuit through the magnet of the indicator connected therewith and the said source of current,and a switch with its connections operated by the called subscribers indicator-magnet for shunting the said magnets from the cord-circuit and including them in the samebridge with the source of current, whereby the signals may be maintained in the condition in which they have been placed, substantially as described.

5. Inatelephone-exchangesystem,the combination with telephone-lines extending from subscribers stations to an exchange, of cordconnecting apparatus at the exchange, indicators at the exchange having their electromagnets normallyincluded serially in a cordstrand, one of the said indicators being connected with the calling subscriber and the other with the called subscriber, a bridge connection between the sides of united telephone-lines including a source of current, the said bridge connection being joined with the normal cord conductor between the said electromagnets, a telephone switch-hook at each subscribers station adapted to close circuit ra O through the magnet of the indicator connected therewith and the said source of current, and a switch with its connections operated by the called subscriber-s Aindicator-magnet for shunting the said magnets from the cord-circuit and including them in parallel relation with each other in, the same bridge with the source of current, whereby the signals may be maintained in the condition in which they have been placed, substantially as described.

6. In a telephone-exchange system,the combination with telephone-lines extending from subscribers telephone stations to an exchange, of indicatorsat the exchange having their electromagnets included serially in the telephone-line uniting the substations, one of the said indicators being connected with the calling subscriber and the other with the called subscriber, a telephoneswitch-hook at each subscribers station adapted to close circuit through the magnet of the indicator connected therewith, and a switch with its connections operated by the called subscribers indicator-magnet for shunting the said magnets from the telephonie circuit and maintaining them in closed circuit, whereby the signals may be maintained in the condition in which they have been placed, substantially as described.

7. In a telephone-exchange system,the combination with telephone-lines extending from subscribers stations to an exchange, of indicators at the exchange having their electromagnets included serially in the telephonie circuit between the subscribers, one of the said indicators being connected with the calling subscriber and the other with the called subscriber, a bridge connection between the sides of united telephone-lines including a source of current, a telephone switch-hook at each subscribers station adapted to close circuit through the magnet of the indicator connected therewith and the said sourcevof current, and a switch with its connections operated by the called subscribers indicatormagnet for shunting the said magnets from the telephonie circuit and including them in the same bridge with the sourcev of current, whereby the signals may be maintained in the condition in which they have been placed, substantially as described.

S. In a telephone-exchange system,the com* bination with telephone-lines extending from subscribers stations to anexchange, of indicators at the exchange having their electromagnets included serially in a side of the telephonie circuit between thev subscribers stations, one of vthe said indicators being connected with the calling subscriber and the other with the called subscriber, a bridge con-v nection between the sides of united telephonelines including a source of current, the said bridge connection being joined with the si'de of the telephonie circuit containing the said electromagnets 'and between the said electromagnets, a telephone switch-hook at each subscribers station adapted to close circuit ICO tion in which they have been placed, sub- 1o stantially as described.

In Witness whereof I hereunto subscribe my name this 8th day of January, A. D. '1901.

WILLIAM M. DAVIS.

"Witnesses:

HARVEY L. HANsoN, HERBERT F. OBERGFELL. 

